1. Field of the Invention
The present invention relates to a storage system, and more particularly to a backup method for data used by a computer system application.
2. Description of the Related Art
Data utilized by an application (will be called “AP” hereinafter) in a host computer may be lost in accordance with “a failure of the storage apparatus”, “the destruction of data by a computer virus”, and “user error”. A “backup” for saving this data as a copy is implemented in a storage apparatus in preparation for a case in which this data is lost. When data used by the AP is lost, the storage apparatus executes a “recovery” to recover the backed up data.
There are various methods for backing up data. One such backup method uses the copy function of the storage apparatus to reduce the impact on the work host computer resulting from a backup. In a case where a data write is generated in accordance with this copy function to the primary storage area of the storage apparatus being used by the AP, the same write data is also written to a secondary storage area inside the same storage apparatus. That is, it is possible to create a secondary storage area for storing data corresponding to the data stored in the primary storage area at all times. Then, when this copy function is split at a certain point in time, it is possible to create in the secondary storage area backup data related to the data stored in the primary storage area at the point in time that the copy function was split.
To recover the data at the point of recovery, this data must be saved in a state in which the consistency of the data is maintained. In order to maintain data consistency, the AP is generally “in quiescent statein quiescent state”. The “quiescence” of the AP is a process in which updated data inside memory is forcibly outputted to disk after suspending the reception of a new transaction related to the pertinent AP. Since AP-specific processing is required in this process, backup software that cooperates with the backup-targeted AP must be available. Furthermore, AP “quiescence” also requires that work processing be suspended for a fixed period of time, lowering work efficiency.
The time at which an AP is able to be recovered using a recovery process (called the “recovery-enabled time” hereinafter) is a function of the backup time. Normally, the backup time is the time at which the backup target was in quiescent state. This time makes it possible to manage the Recovery Point Objective (called the “RPO” hereinafter) when the system suspends operations at the time of a failure. RPO signifies a target point in time up until which data is able to be recovered when data loss and system suspension occur.
One means for acquiring a backup without carrying out AP quiescence is a technique that makes use of server virtualization technology. Server virtualization technology is technology that uses one server computer to construct one or more virtual computers (hereinafter, called either a “virtual server” or a “Virtual Machine (VM)”). Then, respectively different OS and AP may be run on the plurality of virtual servers. In a case where a backup is performed in VM units, the backup is carried out using a VM quiescence function similar to that for the AP. For this reason, when acquiring a VM backup using server virtualization technology, it is possible to backup the AP data residing on the VM without using AP-specific backup software.
As the prior art, the specification for U.S. Pat. No. 7,370,233 and “Understanding VMware Consolidated Backup,” VMware, 2007 are known.
When a backup is performed in VM units as in the prior art, since the AP on the VM is not in quiescent state, there may be a case where an AP-related transaction process is backed up midway through the transaction. When this occurs, the transaction process may be performed over again at recovery in accordance with an AP recovery process (for example, a rollback), and the VM backup time and the AP recovery time can differ.
Up until now, a user carried out an AP recovery by referencing a backup catalog and indicating the data of the time to which he wished to return. However, in a case where a backup is performed in VM units by staticizing the AP, the problem has been that only the VM backup time is capable of being managed and the AP recovery time is indiscernible even by referencing the backup catalog. Accordingly, for the user, this gave rise to the problem that processing that depended on the recovery time, such as AP recovery time-based recovery management, could not be carried out.
Similarly, the backup start time and the AP recovery time may differ when a backup has been executed without staticizing the AP even when the backup is not executed in VM units. For this reason, the problem has been that the user is not able to carry out processing that depends on the recovery time, such as AP recovery time-based recovery management.